Silver maces

Added the silver mace to be the base weapon type of Demonbane.  It is appropriate that an artifact weapon designed to slay Demons would be made of (or plated with) silver.  This helps to offset the damage reduction when Demonbane was changed from a longsword to a mace and makes it more specialized against silver-haters.
Set the probability to 2, equal to that of a silver spear.
Increased the weight of the silver mace by 120% -- equal to the weight increase from a normal spear to a silver spear. (Assuming the weapon is silver plated rather than made entirely out of silver.)
Increased the base cost to 60, a similar increase as spear to silver spear, to be an even number between silver spear and silver saber.
Monsters will prefer silver maces over regular maces.
Otherwise, identical in function to a normal mace.

include/artilist.h

@@ -158,7 +158,7 @@ static NEARDATA struct artifact artilist[] = {
       PHYS(5, 0), NO_DFNS, NO_CARY, 0, A_NONE, NON_PM, NON_PM,
       2, 5, 500L, NO_COLOR, DRAGONBANE),
 
-    A("Demonbane", MACE, (SPFX_RESTR | SPFX_DFLAG2), 0, M2_DEMON,
+    A("Demonbane", SILVER_MACE, (SPFX_RESTR | SPFX_DFLAG2), 0, M2_DEMON,
       PHYS(5, 0), NO_DFNS, NO_CARY, BANISH, A_LAWFUL, PM_CLERIC, NON_PM,
       1, 3, 2500L, NO_COLOR, DEMONBANE),
 

include/objects.h

@@ -352,6 +352,10 @@ WEAPON("mace", NoDes,
        1, 0, 0, 40,  30,   5,  6,  6, 0, B,   P_MACE, IRON, HI_METAL,
                                                         MACE),
         /* +1 small */
+WEAPON("silver mace", NoDes,
+       1, 0, 0,  2,  36,  60,  6,  6, 0, B,   P_MACE, SILVER, HI_SILVER,
+                                                        SILVER_MACE),
+        /* +1 small */
 WEAPON("morning star", NoDes,
        1, 0, 0, 12, 120,  10,  4,  6, 0, B,   P_MORNING_STAR, IRON, HI_METAL,
                                                         MORNING_STAR),

src/weapon.c

@@ -266,6 +266,7 @@ dmgval(struct obj *otmp, struct monst *mon)
         case IRON_CHAIN:
         case CROSSBOW_BOLT:
         case MACE:
+        case SILVER_MACE:
         case WAR_HAMMER:
         case FLAIL:
         case SPETUM:
@@ -686,8 +687,8 @@ static const NEARDATA short hwep[] = {
     TSURUGI, RUNESWORD, DWARVISH_MATTOCK, TWO_HANDED_SWORD, BATTLE_AXE,
     KATANA, UNICORN_HORN, CRYSKNIFE, TRIDENT, LONG_SWORD, ELVEN_BROADSWORD,
     BROADSWORD, SCIMITAR, SILVER_SABER, MORNING_STAR, ELVEN_SHORT_SWORD,
-    DWARVISH_SHORT_SWORD, SHORT_SWORD, ORCISH_SHORT_SWORD, MACE, AXE,
-    DWARVISH_SPEAR, SILVER_SPEAR, ELVEN_SPEAR, SPEAR, ORCISH_SPEAR, FLAIL,
+    DWARVISH_SHORT_SWORD, SHORT_SWORD, ORCISH_SHORT_SWORD, SILVER_MACE, MACE,
+    AXE, DWARVISH_SPEAR, SILVER_SPEAR, ELVEN_SPEAR, SPEAR, ORCISH_SPEAR, FLAIL,
     BULLWHIP, QUARTERSTAFF, JAVELIN, AKLYS, CLUB, PICK_AXE, RUBBER_HOSE,
     WAR_HAMMER, SILVER_DAGGER, ELVEN_DAGGER, DAGGER, ORCISH_DAGGER, ATHAME,
     SCALPEL, KNIFE, WORM_TOOTH